When Spiders Alive! returns to the Museum this Friday, July 4 —two years after the exhibition’s debut—for some of the featured arachnids, it won’t be a question of coming back. As it turns out, they never left—and some have even multiplied.

Just when and how Old World monkeys—a diverse and widespread group that includes macaques, baboons, and leaf monkeys—dispersed out of Africa and into Eurasia has never been fully understood. But a new discovery of an about 7-million-year-old monkey fossil from Abu Dhabi by a team of researchers at institutions around the world, including the American Museum of Natural History, provides important clues to the questions.